Downhole hydraulic pump and engine improvements

ABSTRACT

A downhole hydraulically actuated pump having an engine piston and a pump piston, with the pistons being arranged with diametrically opposed faces which operate within a common fluid chamber. Multiple pump pistons can be actuated by the engine piston so as to enable simultaneous production to occur from a pluraligy of hydrocarbon producing zones, with the produced fluid flowing to the surface of the earth along separate flow paths.

United States Patent Roeder 1 W Nov. 28, 1972 X4 6 smmm 5/// 3HH W44 aam $3 0 cRcR mwmm 9999 nnnn 5736 @@%M new 3333 e. m w A s P 3 m M... m SET B um M Mm DW J Y0 8L HR We E mm H mm m G PM ON w DE h w. m

[22] Filed: Dec. 3, 1970 [21] Appl. No.: 94,905

Primary Examiner-James A. Leppink Attorney-Marcus L. Bates [57] ABSTRACTA downhole hydraulically actuated pump having an [51] Int Cl 1 enginepiston and a pump piston, with the pistons being arranged withdiametrically opposed faces which operate within a common fluid chamber.Multi- [58] Field of Search ........166/l06, 313, 314; 91/222; 417/358,400, 403, 404

ple pumppistons can be actuated by the engine piston so as to enablesimultaneous production to occur from a pluraligy of hydrocarbonproducing zones, with the [5 6] References Cited UNITED STATES PATENTSproduced fluid flowing to the surface of the earth along separate flowpaths.

Sargent .....4l7/400 2,821,141 1/1958Sargent......................417/403 10 Claims, 11 Drawing Figures r allalllll'lfllllll v y r rffllllllfflfl/lllll ,lfl v 1 I PATENTEnunvze I9723,703,926

sum 2 or 2 INVENTOR GEORGE KJZOEDEE MARCUS L.BATES HIS AGENTnllllllllllllnlllil Illl IIIIIIII Ill IIIII III!!! II DOWNHOLE HYDRAULICPUMP AND ENGINE IMPROVEMENTS BACKGROUND OF THE INVENTION Downholeproduction pumps which are actuated by hydraulic fluid pressure appliedfrom the surface of the earth are known to those skilled in the art.Pumps of this design are usually complex and require many coactingworking parts. Prior art examples of these pumps are to be found in mypreviously issued U.S. Pat. No. 3,517,741 and U.S. Pat. No. 3,453,963,to which reference is made for further background of this invention.There is often a need for a simplified pump design which is rugged inconstruction and simple in operation. Also it would be desirable to usea downhole fluid actuated pump in a manner to enable production fromseveral different zones to be produced along separate This inventionsets forth a hydraulic actuated downhole production pump assembly forpumping fluid from one or more fluid producing zones to the ground levelby the provision of a pump assembly having an engine means and a pumpmeans, with the engine means being reciprocated by power fluid whichflows. from a valve means. The valve means is connected to a power fluidsource which originates above ground level. The pump has a cylinderdisposed within a housing which also encloses the engine cylinder; Aportion of the housing forms a common chamber which is always exposed tothe power fluid by means of a hollow passageway which leads through theengine piston, a hollow valve control rod, and to the power fluidsource. Hence, diametrically opposed faces of the pump piston and enginepiston are exposed to the power fluid of the common chamber.

Multiple pump cylinders may be radially spaced apart within the engineand pump housing, with each pump cylinder having the lower extremitythereof connected to a different production zone, and with each pumpoutlet being connected to a different flow conduit for enabling flow offluid along specific and separate flow paths to the surface of theearth.

A standing valve assembly together with a packer means precludes fluidfrom each of the production zones from intermingling with one another.

It is therefore a primary object of the present invention to provide adownhole fluid actuated pump of the free or standing type which has aminimum number of working parts therein.

Another object of the present invehtion is the provision of a downholepump assembly which has a pump cylinder disposed in fluid communicationwith an engine cylinder.

A further object of the present invention is the provision of a downholepump assembly having a single engine connected to a plurality ofproduction pumps, with each pump being connected to produce fluid from adifferent fluid producing formation.

A still further object of the present invention is the provision of adownhole pump and standing valve assembly which enables simultaneousproduction of fluid to be realized from a dual completed well.

Another object of the present invention is the provision of a new methodof producing wells having multiple production zones.

The above and other objects are attained in accordance with the presentinvention by the provision of a downhole fluid actuated pump assemblyhaving an engine with a piston thereof being directly connected to aproduction pump piston and with adjacent piston faces of the pump beingin communication with one another, with a face of the engine piston, andwith the power fluid source, while the remaining face of the enginepiston is alternately exposed to the power fluid source so as to enablethe power fluid to reciprocate the piston of the production pump.

These and other objects and advantages of this invention will becomereadily apparent to those skilled in the art upon reading the followingdetailed description and by referring to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational, partdiagrammatical, view of a downhole production pump made in accordancewith the present invention;

FIG. 2 is an enlarged, longitudinal, cross-sectional, partdiagrammatical view of part of the apparatus seen in FIG. 1;

FIG. 3 is a part diagrammatical, longitudinal, part cross-sectional viewof a pump which could be fabricated as seen in FIG. 2;

FIGS. 4 and 5, respectively, are cross-sectional views taken along line4-4, and 55, respectively, of FIG.

FIG. 6 is a fragmentary, part diagrammatical, longitudinal partcross-sectional view of a downhole pump made in accordance with thepresent invention with the pump being illustrated as operativelydisposed within a borehole;

FIG. 7 is a fragmentary, part cross-sectional, longitudinal view of thepump seen in FIG. 6;

FIG. 8 is a cross-sectional view taken along line 843 of FIG. 7;

FIG. 9 is an enlarged part cross-sectional view of part of the apparatusdisclosed in FIG. 6; v

FIG. 10 is a modification of the pump of FIG. 8; and

FIG. 11, is a schematical representation of the flow path used inconjunction with the downhole pump of FIG. 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Throughout thespecification, wherever possible, like or similar numerals will refer tolike or similar parts.

In FIG. 1, numeral 8 indicates a casing which is disposed within andforms a part of a borehole. Packer 9 prevents fluid flow thereacross andhelps maintain a downhole hydraulically actuated pump assembly 10properly positioned within the borehole. Power fluid enters the valvesection of the pump at 12 while production fluid enters the productionpump section at 14. The produced fluid exists at ports 15 where itinterrningles with the spent power fluid which exits from ports 16, withthe mixed fluids flowing to the surface of the earth and to the tankbattery or the like.

The valve section 17 is operatively connected to an engine and pumpsection which are each preferably disposed within a common housing 18. I

Looking now to the details of FIGS. 2-5, the upper interior portion ofthe pump assembly is seen to be provided with a power fluid inlet 20which exits into a counterbore at 21. A hollow valve control rod 22 isaxially disposed within the counterbore and of the engine workingcylinder 23. Piston chamber 24 reciprocatingly receives engine piston 25therein with the engine piston having diametrically opposed bosses 26,27 for controlling the operation of the valve section and for actuatingthe production pump piston. Power fluid passageway 28 is seen to beformed within the lower boss with the central longitudinal passageway 29extending up through the piston and into communication with the beforementioned hollow valve control rod.

Production piston 30 has a lower face 31 and is sealingly andreciprocatingly received within a production cylinder 32 in the usualmanner so as to force fluid into and out of fluid chamber 32'. Theproduction barrel has an upstanding wall surface 33 attached to a loweradapter 34 so as to form a common chamber which includes annulus 35. Theannulus isin communication with passageways 28, 29, and the interior ofthe hollow control rod. The force of the power fluid is always effectedat 35 by means of the depending end 36 of the hollow control rod. Therod includes a passageway 37 formed in the terminal end thereof which isin flow communication with the hollow control rod and with the ports 28.

Annulus 39 is cyclicly closed by the action of a valve element 43 as theannular groove 40 of the control rod is reciprocated to an upperposition by the engine piston. The inlet check valve 41 is suitablyconnected from the production pump inlet 14 into chamber 32'while'outlet check valve 42 is connected to the production fluid outletport from the chamber 32'. The check valves are well known in the artand can take on several different forms.

Valve element 43 reciprocates within its illustrated bore and has acircumferentially extending groove formed thereabout which cooperateswith the inside peripheral surface of the bore to form an annulus 44.

The annulus flow connects the exhaust port with port 39 on the upwardstroke of the piston. On the downstroke of the power piston the elementuncovers port 39 so as to permit power fluid to flow at 45.

Engine piston face 47 is alternately exposed to power fluid which flowsfrom port 39 and to the exhaust port 16. Piston face 48 is diametricallyopposed to the pump piston face 49, and each of the piston faces arealways in communication with power fluid which is eflected at the end ofthe control rod.

FIGS. 6-11 disclose the method by which a plurality of production pumpsmay be connected to a single engine piston, and fluid produced from aplurality of hydrocarbon producing zones, while the produced fluid fromeachof the zones flows to the surface of the earth along separate flowpaths.

As particularly seen in FIG. 6, a fishing neck 51 along with aconventional hydraulic pump packer means is disposed above seal means52. A foot 9' is provided with a passageway 53 which communicates withannulus 54. The annulus receives fluid from a production zone throughperforations 55. A standing valve assembly 56 has ports 57 formedtherein which may be moved into alignment with passageway 53. Stinger'58is telescopingly received within the standing valve assembly andreceives fluid from inlet 59 by means of a suction port 60 which isformed in the terminal end of the stinger. Hence fluid can flow from alower zone, through perforations 61, and into the stinger. Y

Production fluid from the lower zone exhausts at port 62, flows intoannulus 63, through ports 64 which are formed in the seat, and upthrough production pipe 65 which is located within the casing annulus.Annulus 66 is flow communicated with port 66' and with production tubing67.

Looking to the details of the pump and stinger assembly of FIG. 7, it isseen that the engine piston is provided with radially spaced apartpassageways 128 which are flow connected to the hollow valve controlrod. The lower piston face 148 is connected to a plurality of connectingrods 149, each of which is disposed within a pump barrel or cylinder133', so as to be jointly reciprocated by the piston. Inlet 60 isisolated from inlet 69 by means of they O-ring seal placed at groove 68.Inlet 69 is isolated from outlet 62 by means of packer 70. Outlets 15'and 62 are isolated from one another by means of packer 19'.

As disclosed in FIG. 9, the standing valve assembly has a conical shapedaxially aligned passageway 81 which sealingly receives seal means 70 ofthe pump. Central member 71 of the standing valve assembly istelescopingly received within member 72 so as to communicate or toisolate the various passageways with or from one another: The standingvalve assembly engages a seat at 73 while a packer 74 isolates annulus75 from inlet ports 53. The telescoping member has a lowerniost portion76 which is biased in an upward direction by means of the illustratedspring. Ports 77 are aligned with ports 78 while annulus 79 is alignedwith ports 80. Annulus 81 is isolated from annulus 83 by means of seal70, with annulus 83 being in communication with passageway 84 and 64.Passageway 84 communicates with chamber 85.

As seen in FIG. 10, the engine pump can be connected to a multiplicityof difi'erent production pumps, as for example, three. Each of theproduction pumps may be connected to a different production zone byextending the teachings of FIGS. 1 and 9. As seen in FIG. 10, a pumpcylinder 233 has a pump rod 249 disposed therein with power fluidflowing through piston 248 by means of passageways 228.

As seen in the diagrammatical representation of FIG. 11, flow to andfrom each of the pump pistons may be attained by providing spaced apartpackers 86 and 87 for isolating production zone A from production zonesB and C. This enables production fluid from zone A to enter the terminalend of the stinger, production fluid from zone B to flow down the casingannulus and into a port located in the foot; and for production C toflow from above packer 87 and into another isolated portion of the foot.

Spaced apart production ports 90 are isolated from one another by theillustrated spaced apart packers 89. Flow from the production ports flowupwardly at A, B, with the production C also including the spent powerfluid.

OPERATION being known to those skilled in the art. With the pumpproperly positioned within the borehole in the illustrated manner ofFIGS. 1-5, production fluid from a fluid producing zone enters at thepump suction or inlet 14 as the piston 30 is reciprocated by the engine.Check valve 41 enables fluid to flow through passageway 50 and into thechamber 32 on each upstroke of the piston, while check valve 42 permitsflow of fluid from chamber 32 and through production port on eachdownstroke of the pump piston.

As the engine reciprocates the piston 30, the diametrically opposedpiston faces 48, 49 are continuously exposed to power fluid which flowsfrom 38, 37, 29, 28, and into chamber 35. Hence, piston face 47 musthave an area which is of a proper ratio with respect to the piston face49 so as to provide sufficient force to cause the fluid within chamber32' to flow to the surface of the ground.

In order to downstroke piston 25, fluid enters at 38, 39, 45, and flowsinto the upper cylinder chamber by means of port 20, thereby forcing thepiston in a downward direction. As the piston reaches its lowerextremity of travel, valve element 43 is shifted by the action of groove40 into its uppermost position, whereupon port 39 is now connected tothe spent power fluid outlets by means of annulus 44. This actionpermits power fluid to flow at 29 into chamber 35 thereby forcing thepiston in an upward direction due to the difference in the exposedsurface area between pistons 48 and 49.

In order to simultaneously produce fluid from two different productionzones, radially spaced apart passageways 128 are provided in the enginepiston 25, and a pump piston and cylinder assembly arranged with thepump end being paced in communication with each of the individualproducing zones by the employment of the illustrated seat and valveassembly, the details of which are more particularly set forth in myabove referred to US. Pat. No. 3,517,741. Where fluid is being producedfrom a plurality of fluid producing zones, fluid from the lower zoneflows at 59 up through the illustrated annulus into ports 77 and 78where the fluid then enters the hollow stinger and flows into chamber132 where the pump piston forces the fluid through the production port62, into annulus 83, passageway 64, up through the production tubing 65,and then to the surface of the earth.

At the same time, fluid from a fluid producing zone and within casingannulus 8 is flow communicated with port 53, annulus 79, port 80,annulus 81, port 69, with the last port being in fluid communicationwith another of the production chambers which enables the fluid to beforced through outlet 15' where the fluid then flows into the annulusabout the pump, into port 66, and up the production tubing 67 along withthe spent power fluid.

When the free pump 118 is desired to be retrieved, power fluid is pumpeddown production tubing 65 thereby forcing the pump from its seat,whereupon the pump travels to the surface of the earth. At the same timemember 71 is forced in an upward direction with respect to member 72,thereby misaligning ports 78 and 80 with their respective ports in orderto isolate each of the production zones from one another.

After the pump has been serviced, it can be pumped back downhole whereit will again assume the illustrated position of FIG 9.

I claim: 1. A hydraulic actuated downhole production pump assembly forpumping fluid from a fluid producing zone to ground level;

said pump assembly including engine means, pump means, power fluid inletmeans, spent power fluid outlet means, production fluid inlet means, andproduction fluid outlet means;

said engine having a control valve means, a working cylinder, an enginepiston reciprocatingly received within said working cylinder anddividing said cylinder into a lower and upper chamber, a hollow valvecontrol rod attached to said engine piston and connected to said valvemeans for moving said valve means from a first to a second position inresponse to the position of said engine piston;

said pump means having a pump cylinder, a production pistonreciprocatingly received within said pump cylinder and dividing saidpump cylinder into a lower and an upper chamber, a connecting rodaffixed to said engine piston and to said production piston, pump valvemeans connecting said production fluid inlet means and said productionfluid outlet means to the lower chamber of said pump cylinder to enableproduction fluid to be forced through said pump means;

means connecting said power fluid inlet means to said hollow valvecontrol rod, means forming a passageway from said hollow valve controlrod, through said engine piston, and into the lower chamber of saidworking cylinder;

said lower chamber of said working cylinder being in communication withsaid upper chamber of said pump cylinder;

said control valve means, when in the first position,

connects said power fluid to said upper chamber of said workingcylinder;

said control valve means, when in the second position, connects saidupper chamber of said working cylinder to said spent power fluid outletmeans to thereby cause said engine means to reciprocate said pumppiston.

2. The downhole production pump assembly of claim 1, and furtherincluding a second pump cylinder radially spaced apart from the firstrecited pump cylinder; a second production piston reciprocatinglyreceived within said second pump cylinder and dividing said second pumpcylinder into a lower and upper chamber; a second connecting rod affixedto said engine piston and to said second production piston;

another pump valve means connected to the last recited lower chamber forconducting fluid flow from another production fluid inlet to anotherproduction fluid outlet;

the last recited upper chamber being in fluid communication with theupper chamber of the first recited pump cylinder and with the lowerchamber of said working cylinder.

3. The improvement of claim 2, and further including means by which thelower chamber of said second pump cylinder is flow connected to anotherproduction zone which is spaced apart from the first recited fluidproducing zone.

4. The improvement of claim 2, and further including means forming ahollow stinger, said stinger being affixed to and depending from saidpump means the interior of said stinger forming the first recitedproduction fluid inlet;

a standing valve assembly including a member,

means by which said member is attached to structure associated with awell bore; a central member telescopingly received within said member,means forming a central bore through said central member for slidablyreceiving said stinger therein;

means forming spaced apartports in said member, means forming spacedapart ports in said central member, means by which one of each port insaid member is aligned with one of said ports in said central memberwhen said central member is in a first position with respect to saidmember, and misaligned with respect to each other when said centralmember is in a second position with respect to said member; meansforming a flow path which enables fluid to flow from one fluid producingformation, through a pair of alignedports, and into said hollow stinger;means forming a flow path which enables fluid to flow from another fluidproducing formation, through another pair of aligned ports, and into thefirst recited production inlet; whereby, fluid produced from two spacedapart formations can be produced by the pump and caused to flow alongseparate flow paths.

5. The improvement of claim 4, and further including means forming aflow path from one of said production outlets to the surface of theground; means forming another flow path from the second recitedproduction outlet to the surface of the ground, whereby:

said pump, when properly seated on said central member, produces fluidfrom two spaced apart production zones along separate flow paths, and;when said pump is removed from said central member, the central membermoves with respect to said member to thereby misalign the pairs of portsin said member and said central member to thereby preclude interminglingfluid from the spaced apart fluid producing zones.

6. A pump assembly for pumping a produced fluid from a production fluidinlet to a production fluid outlet by using a power fluid;

said pump assembly including means forming an engine, a pump, a powerfluid inlet, a spent power fluid outlet, a production fluid inlet, and aproduced fluid outlet;

said engine having a valve means, a working cylinder,

an engine piston, a hollow valve control rod extending from said pistonand to said valve means for controlling the action of said valve means;

said pump including a pump cylinder which is located within a dependingmarginal portion of said working cylinder, a pump piston reciprocatinglyreceived within said pump cylinder; means interconnecting said enginepiston to said pump piston;

check valve mean by which one end of said pump cylinder is connected tosaid production fluid inlet and to said production fluid outlet to causeproduction fluid to be pumped when said pump piston is reciprocated bysaid engine;

said pump cylinder and said working cylinder having adjacent endportions in fluid communication with each other;

means forming a flow path for conducting power fluid from said powerfluid inlet, through said hollow valve control rod, through said enginepiston,

and into fluid communication with the adjacent end portions of theworking cylinder and pump cylinder;

said valve means connecting the power fluid inlet to a cylinder chamberformed by the portion of the working cylinder above said engine pistonwhen said hollow control rod is moved into one position by the enginepiston; and, said valve means connecting the spent power fluid outlet tosaid cylinder chamber of the working cylinder above said engine pistonwhen said hollow controllrod is moved into another position by theengine piston.

. 7. The pump assembly of claim 6, and furtherincluding a second pumpcylinder'radially spaced apart from the first recited pump cylinder; asecond production piston reciprocatingly received within said secondpump cylinder and dividing said second pump cylinder into a lower andupper chamber; a second connecting rod affixed to said engine piston andto said second production piston;

pump valve means connected to the last recited lower chamber forconducting fluid flow from a production fluid inlet to a productionfluid outlet;

the last recited upper chamber being in fluid communication with theupper chamber of the first recited pump cylinder and with the lowerchamber of said working cylinder.

8. The improvement of claim 7, and further including means by which thelower chamber of said second pump cylinder is flow connected to aproduction zone which is spaced apart from the first recited fluidproducing zone. I

9. The improvement of claim 7 and further including means forming ahollow stinger, stinger being affixed to and depending from said pumpassembly, the interior of said stinger forming the recited productionfluid inlet;

a standing valve assembly including a member,

means by which said member is attached to structure of a well bore; acentral member telescopingly received within said member, means forminga central bore through said central member for slidably receiving saidstinger therein;

means forming spaced apart ports in said member, means forming spacedapart ports in said central member, one of each ports in said memberbeing aligned with one of said ports in said central member when saidcentral member is in a first position with respect to said member, andmisaligned with respect to each other when in a second position; meansforming a flow path which enables fluid to flow from one fluid producingformation, through a pair of aligned ports, and into said hollowstinger; means forming a flow path which enables fluid to flow fromanother fluid producing formation, through another pair of alignedports, and into the first recited'production inlet, whereby fluidproduced from two spaced apart formations can be produced along separateflow paths.

when said pump is removed from said central member, the central membermoves with respect to said member to thereby misalign the pairs of portsin said member and said central member to preclude intermingling fluidfrom the spaced apart fluid producing zones.

1. A hydraulic actuated downhole production pump assembly for pumpingfluid from a fluid producing zone to ground level; said pump assemblyincluding engine means, pump means, power fluid inlet means, spent powerfluid outlet means, production fluid inlet means, and production fluidoutlet means; said engine having a control valve means, a workingcylinder, an engine piston reciprocatingly received within said workingcylinder and dividing said cylinder into a lower and upper chamber, ahollow valve control rod attached to said engine piston and connected tosaid valve means for moving said valve means from a first to a secondposition in response to the position of said engine piston; said pumpmeans having a pump cylinder, a production piston reciprocatinglyreceived within said pump cylinder and dividing said pump cylinder intoa lower and an upper chamber, a connecting rod affixed to said enginepiston and to said production piston, pump valve means connecting saidproduction fluid inlet means and said production fluid outlet means tothe lower chamber of said pump cylinder to enable production fluid to beforced through said pump means; means connecting said power fluid inletmeans to said hollow valve control rod, means forming a passageway fromsaid hollow valve control rod, through said engine piston, and into thelower chamber of said working cylinder; said lower chamber of saidworking cylinder being in communication with said upper chamber of saidpump cylinder; said control valve means, when in the first position,connects said power fluid to said upper chamber of said workingcylinder; said control valve means, when in the second position,connects said upper chamber of said working cylinder to said spent powerfluid outlet means to thereby cause said engine means to reciprocatesaid pump piston.
 2. The downhole production pump assembly of claim 1,and further including a second pump cylinder radially spaced apart fromthe first recited pump cylinder; a second production pistonreciprocatingly received within said second pump cylinder and dividingsaid second pump cylinder into a lower and upper chamber; a secondconnecting rod affixed to said engine piston and to said secondproduction piston; another pump valve means connected to the lastrecited lower chamber for conducting fluid flow from another productionfluid inlet to another production fluid outlet; the last recited upperchamber being in fluid communication with the upper chamber of the firstrecited pump cylinder and with the lower chamber of said workingcylinder.
 3. The improvement of claim 2, and further including means bywhich the lower chamber of said second pump cylinder is flow connectedto another production zone which is spaced apart from the first recitedfluid producing zone.
 4. The improvement of claim 2, and furtherincluding means forming a hollow stInger, said stinger being affixed toand depending from said pump means the interior of said stinger formingthe first recited production fluid inlet; a standing valve assemblyincluding a member, means by which said member is attached to structureassociated with a well bore; a central member telescopingly receivedwithin said member, means forming a central bore through said centralmember for slidably receiving said stinger therein; means forming spacedapart ports in said member, means forming spaced apart ports in saidcentral member, means by which one of each port in said member isaligned with one of said ports in said central member when said centralmember is in a first position with respect to said member, andmisaligned with respect to each other when said central member is in asecond position with respect to said member; means forming a flow pathwhich enables fluid to flow from one fluid producing formation, througha pair of aligned ports, and into said hollow stinger; means forming aflow path which enables fluid to flow from another fluid producingformation, through another pair of aligned ports, and into the firstrecited production inlet; whereby, fluid produced from two spaced apartformations can be produced by the pump and caused to flow along separateflow paths.
 5. The improvement of claim 4, and further including meansforming a flow path from one of said production outlets to the surfaceof the ground; means forming another flow path from the second recitedproduction outlet to the surface of the ground, whereby: said pump, whenproperly seated on said central member, produces fluid from two spacedapart production zones along separate flow paths, and; when said pump isremoved from said central member, the central member moves with respectto said member to thereby misalign the pairs of ports in said member andsaid central member to thereby preclude intermingling fluid from thespaced apart fluid producing zones.
 6. A pump assembly for pumping aproduced fluid from a production fluid inlet to a production fluidoutlet by using a power fluid; said pump assembly including meansforming an engine, a pump, a power fluid inlet, a spent power fluidoutlet, a production fluid inlet, and a produced fluid outlet; saidengine having a valve means, a working cylinder, an engine piston, ahollow valve control rod extending from said piston and to said valvemeans for controlling the action of said valve means; said pumpincluding a pump cylinder which is located within a depending marginalportion of said working cylinder, a pump piston reciprocatingly receivedwithin said pump cylinder; means interconnecting said engine piston tosaid pump piston; check valve mean by which one end of said pumpcylinder is connected to said production fluid inlet and to saidproduction fluid outlet to cause production fluid to be pumped when saidpump piston is reciprocated by said engine; said pump cylinder and saidworking cylinder having adjacent end portions in fluid communicationwith each other; means forming a flow path for conducting power fluidfrom said power fluid inlet, through said hollow valve control rod,through said engine piston, and into fluid communication with theadjacent end portions of the working cylinder and pump cylinder; saidvalve means connecting the power fluid inlet to a cylinder chamberformed by the portion of the working cylinder above said engine pistonwhen said hollow control rod is moved into one position by the enginepiston; and, said valve means connecting the spent power fluid outlet tosaid cylinder chamber of the working cylinder above said engine pistonwhen said hollow control rod is moved into another position by theengine piston.
 7. The pump assembly of claim 6, and further including asecond pump cylinder radially spaced apart from the first recited pumpcylinder; a second production piston reciprocatingly received withinsaid second pump cylinder and dividing said Second pump cylinder into alower and upper chamber; a second connecting rod affixed to said enginepiston and to said second production piston; pump valve means connectedto the last recited lower chamber for conducting fluid flow from aproduction fluid inlet to a production fluid outlet; the last recitedupper chamber being in fluid communication with the upper chamber of thefirst recited pump cylinder and with the lower chamber of said workingcylinder.
 8. The improvement of claim 7, and further including means bywhich the lower chamber of said second pump cylinder is flow connectedto a production zone which is spaced apart from the first recited fluidproducing zone.
 9. The improvement of claim 7 and further includingmeans forming a hollow stinger, stinger being affixed to and dependingfrom said pump assembly, the interior of said stinger forming therecited production fluid inlet; a standing valve assembly including amember, means by which said member is attached to structure of a wellbore; a central member telescopingly received within said member, meansforming a central bore through said central member for slidablyreceiving said stinger therein; means forming spaced apart ports in saidmember, means forming spaced apart ports in said central member, one ofeach ports in said member being aligned with one of said ports in saidcentral member when said central member is in a first position withrespect to said member, and misaligned with respect to each other whenin a second position; means forming a flow path which enables fluid toflow from one fluid producing formation, through a pair of alignedports, and into said hollow stinger; means forming a flow path whichenables fluid to flow from another fluid producing formation, throughanother pair of aligned ports, and into the first recited productioninlet, whereby fluid produced from two spaced apart formations can beproduced along separate flow paths.
 10. The improvement of claim 9, andfurther including means forming a flow path from one of said productionoutlets to the surface of the ground; means forming another flow pathfrom the second recited production outlet to the surface of the ground,whereby: said pump, when properly seated on said central member,produces fluid from two spaced apart production zones along separateflow paths, and; when said pump is removed from said central member, thecentral member moves with respect to said member to thereby misalign thepairs of ports in said member and said central member to precludeintermingling fluid from the spaced apart fluid producing zones.